So I've spent some time researching and the results are that older and cheaper cranksets use steel, which has a weight penalty vs alu, but more significantly imo has a tendency to get bent while aluminum seems to resist bending.
Steel may resist wear to chainring teeth better.
7075 alloy alu appears to be the best material for use in chainrings.
As I am looking for parts for an 8 speed bike, most 8 speed cranksets use cheap steel, and it is hard to tell what a crankset uses.
The eclypse r9 crankset has caught my interest because it uses 7075 alu